diff --git a/CMakeLists.txt b/CMakeLists.txt
index b3644d2..c1fa076 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,6 +6,9 @@ project(dynarr
     LANGUAGES C
 )
 
+add_compile_options(-fsanitize=address)
+add_link_options(-fsanitize=address)
+
 set(CMAKE_C_STANDARD 17)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
diff --git a/src/dyn_arr.c b/src/dyn_arr.c
index 187ab9d..38e2584 100644
--- a/src/dyn_arr.c
+++ b/src/dyn_arr.c
@@ -1,5 +1,6 @@
 // Special thanks to https://bytesbeneath.com/p/dynamic-arrays-in-c
 #include "dyn_arr.h"
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -10,8 +11,11 @@ void *dyn_arr_init(size_t item_size, size_t capacity) {
   void *dyna_ptr = NULL;
   size_t size = item_size * capacity + sizeof(dyna_header);
   dyna_header *header = malloc(size);
+  printf("Pointer init: %p %p\n", header, header + 1);
+  printf("Pointer pop: %p %zu\n", header, item_size);
 
   if (header) {
+    header->item_size = item_size;
     header->capacity = capacity;
     header->length = 0;
     dyna_ptr = header + 1;
@@ -20,11 +24,15 @@ void *dyn_arr_init(size_t item_size, size_t capacity) {
   return dyna_ptr;
 }
 
-void *dyna_ensure_capacity(void *array, size_t item_count, size_t item_size) {
+void *dyna_ensure_capacity(void *array, int64_t item_count) {
+  size_t item_size = dyna_item_size(array);
   dyna_header *header = dyna_get_header(array);
   size_t minimum_capacity = header->length + item_count;
+  size_t maximum_capacity =
+      header->length + item_count * ARRAY_GROWTH_MULTIPLIER;
 
-  if (header->capacity > minimum_capacity) {
+  if (header->capacity > minimum_capacity &&
+      header->capacity < maximum_capacity) {
     return header + 1;
   }
 
@@ -35,6 +43,7 @@ void *dyna_ensure_capacity(void *array, size_t item_count, size_t item_size) {
 
   size_t new_size = sizeof(dyna_header) + new_capacity * item_size;
   header = realloc(header, new_size);
+  printf("Pointer capacity: %p %p\n", header, header + 1);
   header->capacity = new_capacity;
   return header + 1;
 }
@@ -55,13 +64,18 @@ void dyn_arr_pop(void *array, size_t item_size) {
   size_t new_capacity = dyna_length(array) * ARRAY_GROWTH_MULTIPLIER;
   dyna_capacity(array) = new_capacity;
 
-  size_t new_size = sizeof(dyna_header) + new_capacity * item_size;
-  dyna_header *header = dyna_get_header(array);
+  size_t new_size = sizeof(dyna_header) + (new_capacity * item_size);
+
+  dyna_header *header;
   header = realloc(dyna_get_header(array), new_size);
+  array = header + 1;
+  printf("Pointer pop: %p %p %zu\n", header, array, item_size);
 }
 
 void dyna_deinit(void *array) {
+  printf("Pointer deinit: %p\n", array);
   free(dyna_get_header(array));
+  array = NULL;
 }
 
 bool dyna_empty(void *array) {
diff --git a/src/dyn_arr.h b/src/dyn_arr.h
index cebddef..180974c 100644
--- a/src/dyn_arr.h
+++ b/src/dyn_arr.h
@@ -21,6 +21,7 @@
  */
 
 typedef struct dyna_header {
+  size_t item_size;
   size_t capacity;
   size_t length;
 } dyna_header;
@@ -31,19 +32,23 @@ void *dyn_arr_init(size_t item_size, size_t capacity);
 
 // Modification
 #define dyna_append(array, value)                                              \
-  ((array) = dyna_ensure_capacity(array, 1, sizeof(value)),                    \
+  ((array) = dyna_ensure_capacity(array, 1),                                   \
    (array)[dyna_get_header(array)->length] = (value),                          \
    &(array)[dyna_get_header(array)->length++])
 
-void *dyna_ensure_capacity(void *array, size_t item_count, size_t item_size);
+void *dyna_ensure_capacity(void *array, int64_t item_count);
+
+#define dyna_pop(array)                                                        \
+  ((array) = dyna_ensure_capacity(array, -1),                                  \
+   &(array)[dyna_get_header(array)->length--])
 
-#define dyna_pop(array) dyn_arr_pop(array, sizeof(typeof(*array)))
 void dyn_arr_pop(void *array, size_t item_size);
 
 void dyna_deinit(void *array);
 
 // Get meta data
-#define dyna_get_header(array) ((dyna_header *)(array)-1)
+#define dyna_get_header(array) ((dyna_header *)(array) - 1)
+#define dyna_item_size(array) (dyna_get_header(array)->item_size)
 #define dyna_length(array) (dyna_get_header(array)->length)
 #define dyna_capacity(array) (dyna_get_header(array)->capacity)
 bool dyna_empty(void *array);
diff --git a/src/main.c b/src/main.c
index 9b24bce..4e92e37 100644
--- a/src/main.c
+++ b/src/main.c
@@ -6,17 +6,19 @@
 int main() {
   uint64_t *dyna_array = dyna_init(uint64_t);
 
-  for (uint64_t i = 0; i < 9999999; i++) {
+  for (uint64_t i = 0; i < 9; i++) {
     dyna_append(dyna_array, i);
     printf("length: %zu capacity: %zu\n", dyna_array[i],
            dyna_capacity(dyna_array));
   }
 
-  for (uint64_t i = 9999999; i > 0; i--) {
+  for (uint64_t i = 9; i > 0; i--) {
     printf("length: %zu capacity: %zu\n", dyna_array[i],
            dyna_capacity(dyna_array));
     dyna_pop(dyna_array);
   }
 
+  dyna_deinit(dyna_array);
+
   return EXIT_SUCCESS;
 }